【 Weak current College 】 basics-screen--Power By 【 China power house network 】

The gain of the screen
Gain is a numeric representation of the curtain material intrinsic reflection characteristics (all angles of bright degree). To completely random scattering surface (i.e. around 180 degrees direction of reflectivity are the same reflection surface) projection of light, reflection brightness is set to 1. And then in the same conditions, to the screen orientation of the vertical projection of the same light, the determination of the center point and the same arc on the brightness of each point, the brightness and the brightness of the full diffuse scattering of ratio is called the gain of the screen.
Half screen brightness gain is an important indicator. Means the screen center vertical screen direction when viewed as most of the screen, when the viewer off screen axis watch, screen brightness decreases as the highest brightness gain half-time. In addition, the screen gain reduced to half of the observation angle--half gain angle, as well as screen technology has an important indicator. The larger half gain perspective, we can clearly see the contents of the screen.
Screen gain influence on the image
There is no gain screen rendered images more calm and faithful, but is vulnerable to environmental and external influence of the light. And there are gains of the screen is bright, rich layers, colorful pictures and the environment and external light on its impact is relatively small. But the gain of the screen and the screen angle of observation have different inverse relationship, that is, the higher the gain perspective will be smaller. Gain too high (half gain angle too small) will cause the screen to middle-Liang, four corner dark effect and high brightness of some appear saturated with no sense of depth; because energy is too centralized, so horizontal only one or two seats to watch the Ming, bright screen. Therefore, depending on the application should be the appropriate choice of the projection screen, the screen does gain the higher the better.
The aspect ratio of the screen:
The aspect ratio of the projection screen directly affects the quality of the picture, only the aspect ratio of the projection screen and projector natural resolution, the resolution of the signal source (resolution) fit, which makes the display more exciting. The aspect ratio of the projection screen are the following:
1, 4: 3/1.33: 1, mainly for the video image, diagonal/PC x0.8 = width
2, 16: 9/1.78: 1, mainly for high-definition television (HDTV)
3, 1.85: 1, mainly for widescreen TV signal image
4, 2.35: 1, mainly used in widescreen stereo image display
Currently 4: 3, 16: 9 video home commonly used, the user can according to their own machine zoom option in what percentage of the screen.
Screen resolution, contrast, uniformity
Screen resolution (resolution):
In response to the current international different projector type, image resolution based primarily on the type of projector: CRT technology and LCD, DLP, and LCOS technology into D-ILA, bandwidth and pixels.
Pixel: pixel mean resolution height pixel multiplied by the number of results, the main measure LCD/DLP/D-ILA/LCOS technology projectors. At the same time means the true resolution projectors.
Bandwidth: measuring CRT projector per second scan horizontal frequency.
Fresnel optics rear projection (projector behind the screen, projector and viewers on both sides of the screen respectively in the direction of the projection mode) shadow screen because the Fresnel lens Groove and surface double convex (columnar) lens pitch lines, has a direct impact on the resolution of the screen. For diffuse backlight hard curtain, Cork and the projection screen, no Groove spacing of lines of resolution is very high, and meet the needs of the high resolution screen.
The contrast of the screen:
Contrast for images of uniformity and resolution is important primarily means a high level and low level of popular is the screenlight areas and dark areas of the ratio. High-contrast screen display for screen level is critical.
Screen uniformity:
Screen uniformity is not only manifested in the screen above, but also of quality and projector projection technology. Good uniformity can ensure screen horizontally, vertically, from 0-180 ° watch, screen brightness, and color consistency. Screen surface material for uniformity on the projector screen uniformity played a good complement.
The selection screen of the basic requirements
The selection screen, typically to a comprehensive view of the above parameters, combined with practical requirements. One of the following a few key points that need to meet.
1. the screen surface must absolutely vertical. This seemingly simple reasonable requests, but in reality, there will be many screen unevenness of the "wave" of the situation, when the image projection above occurs. But before and after the rough side of the screen, but also easy to cause the projection distance of difference, the last result af cannot influence the precision, the sharpness of the image.
2. screen reflection characteristics must be accurate. Most of the screen looks are white, but in fact different curtain material for light reflection characteristics are different, different color light reflectance.
In commonly used two positive vote curtain material make a comparison,
Diffuse screen
Diffuse scattering screen projector incident light in all directions uniformly diffuse in every angle to see the same image. Diffuse screen with super wide range of audio-visual and soft images, but it is necessary to pay attention to external light clutter light effects. On the external lights, light clutter, outside lighting, messy lighting and image of the scattering of light, reflection, and image light overlaps thus cause poor image quality. Usually diffuse scattering of light without external screen, random light special screening room use to maximize it performance.
The walls also have diffuse scattering characteristics, but without color correction and no absorption, and other processing, use as a screen is displayed when the color of the image appears to be inaccurate, dispersion, dark appear xuguang, brightness, and contrast is not enough. Therefore it is often mentioned in the wall for the screen and is not a correct choice.
Regression type screen
Bead curtain as the curtain surface of glass beads in the direction of incidence of light projection forHeart will light reflection, so usually audio-visual location you can see the bright image. Due to a certain extent, diffuse scattering of the screen in front of the screen to see the image and in the vicinity of the point of a larger location to see the brightness of the image. Near the front of the screen, you can see the brightness, contrast, levels are very good image.
On the external lights, light clutter, as is the light along the external screen, random light reflection in the direction of incidence back, so projector image light and external light, light clutter, so rarely overlap can be bright image.
For these two different types of curtain feed select recommends:
(1). the higher number of ornamental or mix of business with high-brightness projectors advisable to select a wide viewing angle and low gain of the screen.
(2). the selection of appropriate gain of the screen, and help to increase the contrast of the screen, so that the image is grayscale, vibrant, increase the observability of the image.
(3). the good effects of shading and absorption of places you can use the diffuse reflectance and regression type screen, select the family living room should return to the screen.
(4). the projector desktop display you can choose any of the screen and projector hoisting should select the diffuse reflectance or half-value angle larger screen.
3. tie watch distance
Screen size for generic inches, such as 80-inch, 120 inches. Because of the focus distance of projector determines the distance between it and the screen, depending on the distance between them, and install the screen room height and width, you can calculate how much you should install the dimensions of the screen. (Below)
Viewing distance is generally valid screen height of three to five times. Viewing distance also has certain adaptation period: the first use of five times the screen height distance feel more comfortable, you will feel after three times screen height distance more sense of shock.
4. tie installation conditions
Projector install purchase curtain material also have requirements. Because diffuse scattering screen (white plastic curtain) it will have on the incidence of projection light in all directions, so the projector reflection is lifting effect on picture quality. Regression of curtain (bead curtain) is different, as the light source where it came to where direct reflection back. Ordinary bead screen, because the Visual angle is narrow, projector, with installation in the normal viewing height will feel when compared to standing height of the screen to be dark, picture quality.
5. tie installation height
Ideal screen installation height is to let the screen effectively in the center of the screen and the viewer's eyes are on the same horizontal position on a slightly higher. Many screen manufacturers tend to ignore this point, to reduce costs, production screen, the screen above the black parts manufacturing is extremely short, when the installation screen, floors higher use environment, too short edged the screen off the ground is too high, users must to a large angle bottom picture, viewing comfort and long bottom also affect the health of the Viewer.